1/*
2 * A generic kernel FIFO implementation
3 *
4 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 *
20 */
21
22#include <linux/kernel.h>
23#include <linux/export.h>
24#include <linux/slab.h>
25#include <linux/err.h>
26#include <linux/log2.h>
27#include <linux/uaccess.h>
28#include <linux/kfifo.h>
29
30/*
31 * internal helper to calculate the unused elements in a fifo
32 */
33static inline unsigned int kfifo_unused(struct __kfifo *fifo)
34{
35	return (fifo->mask + 1) - (fifo->in - fifo->out);
36}
37
38int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
39		size_t esize, gfp_t gfp_mask)
40{
41	/*
42	 * round down to the next power of 2, since our 'let the indices
43	 * wrap' technique works only in this case.
44	 */
45	size = roundup_pow_of_two(size);
46
47	fifo->in = 0;
48	fifo->out = 0;
49	fifo->esize = esize;
50
51	if (size < 2) {
52		fifo->data = NULL;
53		fifo->mask = 0;
54		return -EINVAL;
55	}
56
57	fifo->data = kmalloc(size * esize, gfp_mask);
58
59	if (!fifo->data) {
60		fifo->mask = 0;
61		return -ENOMEM;
62	}
63	fifo->mask = size - 1;
64
65	return 0;
66}
67EXPORT_SYMBOL(__kfifo_alloc);
68
69void __kfifo_free(struct __kfifo *fifo)
70{
71	kfree(fifo->data);
72	fifo->in = 0;
73	fifo->out = 0;
74	fifo->esize = 0;
75	fifo->data = NULL;
76	fifo->mask = 0;
77}
78EXPORT_SYMBOL(__kfifo_free);
79
80int __kfifo_init(struct __kfifo *fifo, void *buffer,
81		unsigned int size, size_t esize)
82{
83	size /= esize;
84
85	size = roundup_pow_of_two(size);
86
87	fifo->in = 0;
88	fifo->out = 0;
89	fifo->esize = esize;
90	fifo->data = buffer;
91
92	if (size < 2) {
93		fifo->mask = 0;
94		return -EINVAL;
95	}
96	fifo->mask = size - 1;
97
98	return 0;
99}
100EXPORT_SYMBOL(__kfifo_init);
101
102static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
103		unsigned int len, unsigned int off)
104{
105	unsigned int size = fifo->mask + 1;
106	unsigned int esize = fifo->esize;
107	unsigned int l;
108
109	off &= fifo->mask;
110	if (esize != 1) {
111		off *= esize;
112		size *= esize;
113		len *= esize;
114	}
115	l = min(len, size - off);
116
117	memcpy(fifo->data + off, src, l);
118	memcpy(fifo->data, src + l, len - l);
119	/*
120	 * make sure that the data in the fifo is up to date before
121	 * incrementing the fifo->in index counter
122	 */
123	smp_wmb();
124}
125
126unsigned int __kfifo_in(struct __kfifo *fifo,
127		const void *buf, unsigned int len)
128{
129	unsigned int l;
130
131	l = kfifo_unused(fifo);
132	if (len > l)
133		len = l;
134
135	kfifo_copy_in(fifo, buf, len, fifo->in);
136	fifo->in += len;
137	return len;
138}
139EXPORT_SYMBOL(__kfifo_in);
140
141static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
142		unsigned int len, unsigned int off)
143{
144	unsigned int size = fifo->mask + 1;
145	unsigned int esize = fifo->esize;
146	unsigned int l;
147
148	off &= fifo->mask;
149	if (esize != 1) {
150		off *= esize;
151		size *= esize;
152		len *= esize;
153	}
154	l = min(len, size - off);
155
156	memcpy(dst, fifo->data + off, l);
157	memcpy(dst + l, fifo->data, len - l);
158	/*
159	 * make sure that the data is copied before
160	 * incrementing the fifo->out index counter
161	 */
162	smp_wmb();
163}
164
165unsigned int __kfifo_out_peek(struct __kfifo *fifo,
166		void *buf, unsigned int len)
167{
168	unsigned int l;
169
170	l = fifo->in - fifo->out;
171	if (len > l)
172		len = l;
173
174	kfifo_copy_out(fifo, buf, len, fifo->out);
175	return len;
176}
177EXPORT_SYMBOL(__kfifo_out_peek);
178
179unsigned int __kfifo_out(struct __kfifo *fifo,
180		void *buf, unsigned int len)
181{
182	len = __kfifo_out_peek(fifo, buf, len);
183	fifo->out += len;
184	return len;
185}
186EXPORT_SYMBOL(__kfifo_out);
187
188static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
189	const void __user *from, unsigned int len, unsigned int off,
190	unsigned int *copied)
191{
192	unsigned int size = fifo->mask + 1;
193	unsigned int esize = fifo->esize;
194	unsigned int l;
195	unsigned long ret;
196
197	off &= fifo->mask;
198	if (esize != 1) {
199		off *= esize;
200		size *= esize;
201		len *= esize;
202	}
203	l = min(len, size - off);
204
205	ret = copy_from_user(fifo->data + off, from, l);
206	if (unlikely(ret))
207		ret = DIV_ROUND_UP(ret + len - l, esize);
208	else {
209		ret = copy_from_user(fifo->data, from + l, len - l);
210		if (unlikely(ret))
211			ret = DIV_ROUND_UP(ret, esize);
212	}
213	/*
214	 * make sure that the data in the fifo is up to date before
215	 * incrementing the fifo->in index counter
216	 */
217	smp_wmb();
218	*copied = len - ret * esize;
219	/* return the number of elements which are not copied */
220	return ret;
221}
222
223int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
224		unsigned long len, unsigned int *copied)
225{
226	unsigned int l;
227	unsigned long ret;
228	unsigned int esize = fifo->esize;
229	int err;
230
231	if (esize != 1)
232		len /= esize;
233
234	l = kfifo_unused(fifo);
235	if (len > l)
236		len = l;
237
238	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
239	if (unlikely(ret)) {
240		len -= ret;
241		err = -EFAULT;
242	} else
243		err = 0;
244	fifo->in += len;
245	return err;
246}
247EXPORT_SYMBOL(__kfifo_from_user);
248
249static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
250		unsigned int len, unsigned int off, unsigned int *copied)
251{
252	unsigned int l;
253	unsigned long ret;
254	unsigned int size = fifo->mask + 1;
255	unsigned int esize = fifo->esize;
256
257	off &= fifo->mask;
258	if (esize != 1) {
259		off *= esize;
260		size *= esize;
261		len *= esize;
262	}
263	l = min(len, size - off);
264
265	ret = copy_to_user(to, fifo->data + off, l);
266	if (unlikely(ret))
267		ret = DIV_ROUND_UP(ret + len - l, esize);
268	else {
269		ret = copy_to_user(to + l, fifo->data, len - l);
270		if (unlikely(ret))
271			ret = DIV_ROUND_UP(ret, esize);
272	}
273	/*
274	 * make sure that the data is copied before
275	 * incrementing the fifo->out index counter
276	 */
277	smp_wmb();
278	*copied = len - ret * esize;
279	/* return the number of elements which are not copied */
280	return ret;
281}
282
283int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
284		unsigned long len, unsigned int *copied)
285{
286	unsigned int l;
287	unsigned long ret;
288	unsigned int esize = fifo->esize;
289	int err;
290
291	if (esize != 1)
292		len /= esize;
293
294	l = fifo->in - fifo->out;
295	if (len > l)
296		len = l;
297	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
298	if (unlikely(ret)) {
299		len -= ret;
300		err = -EFAULT;
301	} else
302		err = 0;
303	fifo->out += len;
304	return err;
305}
306EXPORT_SYMBOL(__kfifo_to_user);
307
308static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
309		int nents, unsigned int len)
310{
311	int n;
312	unsigned int l;
313	unsigned int off;
314	struct page *page;
315
316	if (!nents)
317		return 0;
318
319	if (!len)
320		return 0;
321
322	n = 0;
323	page = virt_to_page(buf);
324	off = offset_in_page(buf);
325	l = 0;
326
327	while (len >= l + PAGE_SIZE - off) {
328		struct page *npage;
329
330		l += PAGE_SIZE;
331		buf += PAGE_SIZE;
332		npage = virt_to_page(buf);
333		if (page_to_phys(page) != page_to_phys(npage) - l) {
334			sg_set_page(sgl, page, l - off, off);
335			sgl = sg_next(sgl);
336			if (++n == nents || sgl == NULL)
337				return n;
338			page = npage;
339			len -= l - off;
340			l = off = 0;
341		}
342	}
343	sg_set_page(sgl, page, len, off);
344	return n + 1;
345}
346
347static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
348		int nents, unsigned int len, unsigned int off)
349{
350	unsigned int size = fifo->mask + 1;
351	unsigned int esize = fifo->esize;
352	unsigned int l;
353	unsigned int n;
354
355	off &= fifo->mask;
356	if (esize != 1) {
357		off *= esize;
358		size *= esize;
359		len *= esize;
360	}
361	l = min(len, size - off);
362
363	n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
364	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
365
366	return n;
367}
368
369unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
370		struct scatterlist *sgl, int nents, unsigned int len)
371{
372	unsigned int l;
373
374	l = kfifo_unused(fifo);
375	if (len > l)
376		len = l;
377
378	return setup_sgl(fifo, sgl, nents, len, fifo->in);
379}
380EXPORT_SYMBOL(__kfifo_dma_in_prepare);
381
382unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
383		struct scatterlist *sgl, int nents, unsigned int len)
384{
385	unsigned int l;
386
387	l = fifo->in - fifo->out;
388	if (len > l)
389		len = l;
390
391	return setup_sgl(fifo, sgl, nents, len, fifo->out);
392}
393EXPORT_SYMBOL(__kfifo_dma_out_prepare);
394
395unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
396{
397	unsigned int max = (1 << (recsize << 3)) - 1;
398
399	if (len > max)
400		return max;
401	return len;
402}
403EXPORT_SYMBOL(__kfifo_max_r);
404
405#define	__KFIFO_PEEK(data, out, mask) \
406	((data)[(out) & (mask)])
407/*
408 * __kfifo_peek_n internal helper function for determinate the length of
409 * the next record in the fifo
410 */
411static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
412{
413	unsigned int l;
414	unsigned int mask = fifo->mask;
415	unsigned char *data = fifo->data;
416
417	l = __KFIFO_PEEK(data, fifo->out, mask);
418
419	if (--recsize)
420		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
421
422	return l;
423}
424
425#define	__KFIFO_POKE(data, in, mask, val) \
426	( \
427	(data)[(in) & (mask)] = (unsigned char)(val) \
428	)
429
430/*
431 * __kfifo_poke_n internal helper function for storeing the length of
432 * the record into the fifo
433 */
434static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
435{
436	unsigned int mask = fifo->mask;
437	unsigned char *data = fifo->data;
438
439	__KFIFO_POKE(data, fifo->in, mask, n);
440
441	if (recsize > 1)
442		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
443}
444
445unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
446{
447	return __kfifo_peek_n(fifo, recsize);
448}
449EXPORT_SYMBOL(__kfifo_len_r);
450
451unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
452		unsigned int len, size_t recsize)
453{
454	if (len + recsize > kfifo_unused(fifo))
455		return 0;
456
457	__kfifo_poke_n(fifo, len, recsize);
458
459	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
460	fifo->in += len + recsize;
461	return len;
462}
463EXPORT_SYMBOL(__kfifo_in_r);
464
465static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
466	void *buf, unsigned int len, size_t recsize, unsigned int *n)
467{
468	*n = __kfifo_peek_n(fifo, recsize);
469
470	if (len > *n)
471		len = *n;
472
473	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
474	return len;
475}
476
477unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
478		unsigned int len, size_t recsize)
479{
480	unsigned int n;
481
482	if (fifo->in == fifo->out)
483		return 0;
484
485	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
486}
487EXPORT_SYMBOL(__kfifo_out_peek_r);
488
489unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
490		unsigned int len, size_t recsize)
491{
492	unsigned int n;
493
494	if (fifo->in == fifo->out)
495		return 0;
496
497	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
498	fifo->out += n + recsize;
499	return len;
500}
501EXPORT_SYMBOL(__kfifo_out_r);
502
503void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
504{
505	unsigned int n;
506
507	n = __kfifo_peek_n(fifo, recsize);
508	fifo->out += n + recsize;
509}
510EXPORT_SYMBOL(__kfifo_skip_r);
511
512int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
513	unsigned long len, unsigned int *copied, size_t recsize)
514{
515	unsigned long ret;
516
517	len = __kfifo_max_r(len, recsize);
518
519	if (len + recsize > kfifo_unused(fifo)) {
520		*copied = 0;
521		return 0;
522	}
523
524	__kfifo_poke_n(fifo, len, recsize);
525
526	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
527	if (unlikely(ret)) {
528		*copied = 0;
529		return -EFAULT;
530	}
531	fifo->in += len + recsize;
532	return 0;
533}
534EXPORT_SYMBOL(__kfifo_from_user_r);
535
536int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
537	unsigned long len, unsigned int *copied, size_t recsize)
538{
539	unsigned long ret;
540	unsigned int n;
541
542	if (fifo->in == fifo->out) {
543		*copied = 0;
544		return 0;
545	}
546
547	n = __kfifo_peek_n(fifo, recsize);
548	if (len > n)
549		len = n;
550
551	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
552	if (unlikely(ret)) {
553		*copied = 0;
554		return -EFAULT;
555	}
556	fifo->out += n + recsize;
557	return 0;
558}
559EXPORT_SYMBOL(__kfifo_to_user_r);
560
561unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
562	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
563{
564	BUG_ON(!nents);
565
566	len = __kfifo_max_r(len, recsize);
567
568	if (len + recsize > kfifo_unused(fifo))
569		return 0;
570
571	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
572}
573EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
574
575void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
576	unsigned int len, size_t recsize)
577{
578	len = __kfifo_max_r(len, recsize);
579	__kfifo_poke_n(fifo, len, recsize);
580	fifo->in += len + recsize;
581}
582EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
583
584unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
585	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
586{
587	BUG_ON(!nents);
588
589	len = __kfifo_max_r(len, recsize);
590
591	if (len + recsize > fifo->in - fifo->out)
592		return 0;
593
594	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
595}
596EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
597
598void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
599{
600	unsigned int len;
601
602	len = __kfifo_peek_n(fifo, recsize);
603	fifo->out += len + recsize;
604}
605EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
606